I have two words for Bret Easton Ellis, who yesterday claimed that a gay actor shouldn't play the part of lady-spanker Christian Grey in the adaptation of Fifty Shades of Grey: Rock Hudson.

Hudson was a man so gay he had a mini, monogrammed man-bag to house his amyl nitrate (I know this because his former lover Armistead Maupin told me). And yet, on-screen, Hudson glistened with heterosexuality. He defined the mid-20th-century romantic lead. In pictures such as Giant and Magnificent Obsession, he made a generation of postwar women swoon and fantasise; they were convinced of his rock solid straightness. When he died of Aids in 1985, many were more shocked that he was gay than he was dead.

But Ellis described the casting of gay TV actor Matt Bomer as "absolutely ludicrous" (bitter, perhaps, that he is no longer being considered for the screenwriting job on the movie). He tweeted, as if addressing Bomer directly: "I don't care how good an actor you are but being married to another man complicates things for playing CG [Christian Grey]."

I am NOT discriminating Matt Bomer because of his sexuality. Fifty Shades of Grey demands an actor that is genuinely into women. Get it?!?

What guff. The notion that gay people can't play straight characters is so naive, it's foetal. Not only can actors do it, but any old gay trundling down Old Compton Street can – on account of the fact that we have all done it for years. Admittedly, I only played straight until I was 14. But most do it for two or three decades, many their whole lives: a part they never chose and that never ends. Now that's method.

Gay men are so convincing as heterosexuals that millions of women around the world have no idea their husbands think about men during intercourse, or never really loved them. We are so convincing we can run countries without a single, "Ooh get her," from the electorate: I'm talking about James Buchanan. We're such great straights, we can have Princess Diana haircuts, wear hot pants and sing about how trapped we feel in the closet and still get away with the pretence (see early George Michael). Freddie Mercury even called his band Queen, and no one knew.

Why are we so good at it? Because opposite sex attraction is all around us, yet we see it from a distance. We study it like an exchange student immersing herself in French. We know more about you than you do us.

Playing a heterosexual male is hardly acting's greatest challenge. I would simply imagine the world was created for my benefit, and that everything and everyone was a receptacle for my ego and penis. Easy. After all, there are only two differences between gay and straight men: the latter spends his life being told he is right and superior. The former is told he is wrong and inferior. The other difference? Gay men admit to liking things up them. Ellis, whose novels didn't merely kick the literary world in the stomach but shone a torch in American society's sociopathic face, seems to not understand a very basic word: acting. A good actor convinces.

This is why Charlize Theron won the Oscar for playing lesbian serial killer Aileen Wuornos in Monster.

This is why great big gay Montgomery Clift was nominated for an Academy Award opposite Elizabeth Taylor in A Place in the Sun, and was so convincing that the American public assumed they were dating.

And this is why Neil Patrick Harris continues to court and convince primetime audiences with his portrayal of skirt-chaser Barney Stinson in How I met Your Mother.

Before Ian McKellen came out in 1988, did anyone think his Hamlet or Macbeth or Romeo was just a little bit gay? Or, since coming out, that his Gandalf is fey?

I urge Ellis to watch Rupert Everett in Dance with a Stranger, for menacing, thrusting heterosexuality.

Or Richard Chamberlain in the Thornbirds. Or Tab Hunter in Battle Cry. And remember that the very gay John Barrowman was considered too heterosexual for the lead in Will and Grace. So they gave it to a heterosexual.

Hollywood, of course, has more closets than an Ikea showroom. Ellis's unfettered rant will only serve to help these private, paranoid worlds stay shut.